1. Field of the Invention
The present invention relates to a magneto-optical record medium on which information such as document files, images or code data are recorded in high density or from which such information are reproduced, and a magneto-optical record/reproduce apparatus using the magneto-optical record medium.
2. Description of the Related Art
A conventional magneto-optical record disk (hereinafter, referred to in short as a record disk) 58 has a structure shown in FIG. 5 and is formed in the following manner. First, part of a plastic substrate 51 is molded using a molding apparatus so as to have a convex and concave pattern corresponding to a desired information signal. On a convex and concave portion where the above convex and concave pattern is formed, a record layer 52 and a protective layer 53 are successively laminated, thereby constructing the record disk 58.
In a magneto-optical record/reproduce apparatus using the record disk 58, a levitated-type magnetic head is sometimes used in order to shorten the access time for accessing information. In the magneto-optical record/reproduce apparatus using such a levitated-type magnetic head, information can be overwritten by modulating a magnetic field. By using the levitated-type magnetic head, it is possible to shorten the time required for inverting the magnetic field in a record/reproduce operation. Such a magneto-optical record/reproduce apparatus is shown in FIG. 6. A conventional magneto-optical record/reproduce apparatus includes a magnetic head 59. The magnetic head 59 is positioned above the record disk 58 during the record/reproduce operation of the apparatus. The magnetic head 59 includes a slider 56 with a magnet coil 57. An optical pickup is provided on the opposite side of the record disk 58. The optical pickup includes a semiconductor laser device 54 and a convergent lens 55.
In the above-mentioned magneto-optical record/reproduce apparatus, a distance between the protective layer 53 of the record disk 58 and the levitated-type magnetic head 59 is 2 to 5 .mu.m, which means that they are positioned extremely close to each other. The distance therebetween is determined for the following reasons. Information are recorded on the record disk 58 in high density, so that a record frequency used for recording information on the record disk 58 is several megahertz. The levitated-type magnetic head 59 is required to invert the magnetic field in a synchronous manner with a record signal having the above record frequency.
In the above-mentioned magneto-optical record/reproduce apparatus of the magnetic field modulation overwriting type, during the rotation of the record disk 58, an air flow occurs between the record disk 58 and the magnetic head 59. During the rotation of the record disk 58, the magnetic head 59 is levitated from the record disk 58 due to the lift caused by the air flow, so that the distance between the magnetic head 59 and the record disk 58 is maintained constant. On the other hand, when the rotation of the record disk 58 is to be stopped, the magnetic head 59 goes down toward the record disk 58 and comes into contact with the protective layer 53 of the record disk 58. At the start and the end of the rotation of the record disk 58, the record disk 58 rotates while the magnetic head 59 is in contact with the record disk 58. Especially when the record disk 58 is to be stopped, the magnetic head 59 is closely in contact with the protective layer 53.
Therefore, at the start of the rotation of the record disk 58, the probability that the magnetic head 59 is damaged is high, and if damaged, the damage is serious. Thus, there arise such problems that the magnetic head 59 erroneously operates during the record/read operation, and that the life time of the magnetic head 59 is shortened. In some cases, the surface of the protective layer 53 of the record disk 58 may have scratches or an undesired convex and concave pattern, which causes such problems that a noise is mixed in the record/reproduce operation and that the life time of the record disk 58 is shortened.